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Chapter 7 Flashcards

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1
Q

Cellular respiration

A

An exergonic process that transfers energy from the bonds in glucose to ATP.

Cellular respiration produces 38 ATP molecules from each glucose molecule.

Other foods (organic molecules) can be used as a source of energy as well.

Cellular respiration includes both aerobic and anaerobic respiration, but is often used to refer to aerobic respiration.

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2
Q

Cellular respiration formula

A

C6H12O6 (glucose) + 6(O2) -> 6(CO2) + 6(H2O) + ATP

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3
Q

Catabolic pathways

A

Catabolic pathways yield energy by oxidizing organic fuels; they release stored energy by breaking down complex molecules.

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4
Q

Fermentation

A

Partial degradation of sugars that occurs without O2.

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5
Q

Aerobic respiration

A

Consumes organic molecules and O2 and yields ATP.

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6
Q

Anaerobic respiration

A

Similar to aerobic respiration, but consumes compounds other than O2.

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7
Q

Electron transfer

A

The transfer of electrons during chemical reactions releases energy stored in organic molecules.

This released energy is ultimately used to synthesize ATP.

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8
Q

Oxidation

A

Removal of electrons

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9
Q

Reduction

A

Addition of electrons

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10
Q

Redox reactions

A

Chemical reactions that transfer electrons between between reactants are called oxidation-reduction reactions, or redox reactions.

Na + Cl -> Na+ (oxidized, lost electrons) + Cl- (reduced, gained electrons)

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11
Q

Oxidizing agent

A

The electron receptor in a redox reaction

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12
Q

Reducing agent

A

The electron donor in a redox reaction

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13
Q

During cellular respiration, _______ is oxidized, and _______ is reduced.

A

fuel (such as glucose), O2

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14
Q

NAD+ (nicotinamide adenine dinucleotide)

A

A coenzyme (electron carrier molecule) used to hold electrons from organic compounds; functions as an oxidizing agent during cellular respiration.

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15
Q

NADH

A

The reduced form of NAD+ that represents stored energy that is tapped into to synthesize ATP.

NADH releases a lot of energy when oxidized and can be used to make ATP.

It can donate electrons during synthesis reactions to energize them.

NADH passes the electrons to the electron transport chain.

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16
Q

Electron transport chain

A

The electron transport chain passes electrons in a series of steps instead of one explosive reaction.

O2 pulls electrons down the chain in an energy-yielding tumble. The energy yielded is used to regenerate ATP.

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17
Q

Stages of cellular respiration

A
  1. Glycolysis
  2. Citric acid cycle
  3. Oxidative phosphorylation
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18
Q

Glycolysis

A

First stage of cellular respiration

Glycolysis begins respiration by breaking glucose, a six-carbon molecule, into two molecules of a three-carbon compound called pyruvate.

A small amount of ATP is formed in glycolysis by substrate-level phosphorylation.

This stage occurs in the cytoplasm.

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19
Q

The citric acid cycle

A

Second stage of cellular respiration

The citric acid cycle breaks down pyruvate into carbon dioxide and supplies the third stage with electrons.

A small amount of ATP is produced by substrate-level phosphorylation.

This stage occurs in the mitochondria.

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20
Q

Oxidative phosphorylation

A

The third stage of cellular respiration

During this stage, electrons are shuttled through the electron transport chain.

As a result, ATP is generated through oxidative phosphorylation associated with chemiosmosis. This stage accounts for almost 90% of the ATP generated by cellular respiration.

This stage occurs in the inner mitochondrion membrane.

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21
Q

For each molecule of glucose degraded to CO2 and water by respiration, the cell makes up to __ molecules of ATP.

A

32

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22
Q

Glycolysis has two major phases

A
  1. Energy investment phase

2. Energy payoff phase

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23
Q

Glycolysis occurs whether or not ___ is present.

A

O2

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24
Q

Energy investment phase of glycolysis

Study These Flashcards
A

Glucose ——>

2 ATP used —> 2 ADP + 2 P

25
Energy payoff phase of glycolysis
``` Glucose (after energy investment phase)———> 4 ADP + 4 P —> 4 ATP formed ———> 2 NAD+ + 4 e- + 4 H+ —> 2 NADH + 2 H+ ———> 2 Pyruvate + 2 H2O ```
26
Net production in glycolysis
Glucose —> 2 Pyruvate + 2 H2O 4 ATP formed - 2 ATP used —> 2 ATP 2 NAD+ + 4 e- + 4 H+ —> 2 NADH + 2 H+
27
Before the citric acid cycle can begin, pyruvate must be converted to ___________, which links glycolysis to the citric acid cycle
acetyl Coenzyme A (acetyl CoA)
28
Oxidation of pyruvate to acetyl CoA
This step is carried out by a multienzyme complex that catalyzes three reactions. O- S-CoA | | C = O ——————
29
Krebs cycle
Another name for the citric acid cycle
30
Citric acid cycle/Krebs cycle
This cycle oxidizes organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn. It has 8 steps, each catalyzed by a specific enzyme. The acetyl group of acetyl CoA joins the cycle by combining with oxaloacetate, forming citrate. The next seven steps decompose the citrate back to oxaloacetate, making the process a cycle. The NADH and FADH2 produced by the cycle relay electrons extracted from food to the electron transport chain.
31
Following glycolysis and the citric acid cycle, _____ and ______ account for most of the energy extracted from food.
NADH, FADH2
32
Cristae
The inner membrane of the mitochondrion that contains the electron transport chain.
33
Electron transport chain
The electron transport chain is in the cristae of the mitochondrion. Most of the chain’s components are proteins, which exist in multiprotein complexes. The carriers alternate reduced and oxidized states as they accept and donate electrons. Electrons drop in free energy as they go down the chain and are finally passed to O2, forming H2O.
34
Electron transfer in the electron transport chain causes proteins to pump ___ from the mitochondrial matrix to the intermembrane space.
H+
35
ATP synthase
A membrane enzyme, which uses the exergonic flow of H+ to drive phosphorylation of ATP.
36
Chemiosmosis
The use of energy in a H+ gradient to drive cellular work.
37
Proton-motive force
The H+ gradient is referred to as a proton-motive force, emphasizing its capacity to do work.
38
The energy in a H+ gradient across a membrane couples the redox reactions of the electron transport chain to _____________.
ATP synthesis
39
During cellular respiration, most energy flows in this sequence:
Glucose —> NADH —> electron transport chain —> proton-motive force —> ATP
40
Three different categories of cellular poisons that affect cellular respiration
The first category blocks the electron transport chain (for example: rotenone, cyanide, and carbon monoxide). The oligomycin inhibits ATP synthase. The dinitrophenol makes the membrane leaky to hydrogen ions.
41
Fermentation
An anaerobic cellular process in which bacteria, yeast, or other microorganisms convert organic foods into simpler compounds, and chemical energy (ATP) is produced.
42
Fermentation uses ________________ instead of _______________ to generate ATP.
substrate-level phosphorylation, an electron transport chain
43
Anaerobic respiration uses an electron transport chain with a final electron acceptor other than ___, for example, sulfate.
O2
44
Fermentation consists of _______ plus reactions that regenerate _____.
glycolysis, NAD+
45
Two common types of fermentation
1. Alcohol fermentation | 2. Lactic acid fermentation
46
Alcohol fermentation
In alcohol fermentation, pyruvate is converted into ethanol in two steps. The first step releases CO2. The second step produces ethanol.
47
Alcohol fermentation by _____ is used in brewing, winemaking, and baking.
yeast
48
Lactic acid fermentation
In lactic acid fermentation, pyruvate is reduced by NADH, forming lactate as an end product, with no release of CO2.
49
Lactic acid fermentation by some ______ and _________ is used to make cheese and yogurt.
fungi, bacteria
50
Human muscle cells use _____________________ to generate ATP when O2 is scarce.
lactic acid fermentation
51
__________ buildup in muscle is what causes muscle ache/pain.
Lactic acid
52
Lactic acid produced in human muscle cells is carried to _________ where it can be converted back to pyruvate.
the liver
53
Some important fermentation products
1. Ethanol (produced by Saccharomyces cerevisiae, used in industrial solvents and beverages) 2. Glycerol (produced by Saccharomyces cerevisiae, used in production of explosives) 3. Lactic acid (produced by Lactobacillus bulgaricus, used in pharmaceuticals and food) 4. Acetone and butanol (produced by Clostridium acetobutylicum, used in solvents) 5. α-amylase (produced by Bacillus subtilis, used in starch hydrolysis)
54
Fermentation, anaerobic respiration, and aerobic respiration all use ________ and have _____ as the oxidizing agent.
glycolysis, NAD+
55
Cellular respiration produces ___ ATP per glucose molecule; fermentation produces ___ ATP per glucose molecule.
32; 2
56
Obligate anaerobes
Obligate anaerobes carry out fermentation or anaerobic respiration and cannot survive in the presence of O2.
57
Facultative anaerobes
Yeast and many bacteria are facultative anaerobes, meaning they can survive using either fermentation or cellular respiration. In a facultative anaerobe, pyruvate is a fork in the metabolic road that leads to two alternative catabolic routes.
58
Although glucose is considered to be the primary source of sugar for respiration and fermentation, there are actually three sources of molecules for generation of ATP:
1. Carbohydrates (disaccharides) 2. Proteins (after conversion to amino acids) 3. Fats

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